In drilling wells for oil and gas exploration, understanding the structure and properties of the associated geological formation provides information to aid such exploration. Measurements in a borehole are typically performed to attain this understanding. However, the pressure and temperatures accompanying measurement tools in the borehole of a well can affect operation of these tools in the borehole.
Various tools have been utilized to detect anomalies in casings associated with a drilling operation. For example, U.S. Pat. No. 7,795,864 B2 employs permanent magnets to generate magnetic flux in the casing such that, when the magnetic flux encounters an anomaly, the magnetic field will change directions in a nearby region. A Hall sensor can detect the change of the magnetic field such that signals from detecting the change can be processed to obtain anomaly information. WO 2010/013047 (PCT/GB/2009/050940) uses a coil antenna to induce eddy current in a casing and obtain the casing property by measuring the eddy current phase and strength. The usefulness of such measurements may be related to the precision or quality of the information derived from such measurements.